Nematodes I: Filarids

Question 1

What order are filarids in?

Answer 1

Spirurida

Question 2

What kind of life cycle do spirurids have?

Answer 2

Indirect life cycles

Question 3

What are the intermediate hosts of filarids?

Answer 3

Blood sucking arthropods

Question 4

Describe the vermiform embryo of filarids

Answer 4

Contains only-cell clusters as primordia
Pre-L1 stages
Ingested by IH
L1 to L2 to L3 in IH

Question 5

When do filarids have clearly recognizable organs?

Answer 5

L1

Question 6

What is microfilariae an example of?

Answer 6

Vermiform embryo

Question 7

What is the definitive host of Onchocerca cervicalis?

Answer 7

Equids

Question 8

What is the intermediate host of Onchocerca cervicalis?

Answer 8

Culicodes spp

Question 9

What is the Onchocerca cervicalis life cycle?

Answer 9

L3 infects DH with next blood meal of IH
L3, L4, and adults are in the nuchal ligament
Microfilariae in subdermal connective tissue

Question 10

Where are Onchocerca cervicalis microfilaria?

Answer 10

Widely distributed in dermis
Other subdermal connective tissues
Ocular conjunctivae

Question 11

Where are Onchocerca cervicalis larvae?

Answer 11

Nuchal ligament

Question 12

Where are the Onchocerca cervicalis adults?

Answer 12

Often unnoticed

Woven into the deep connective tissue in the nuchal ligament

Question 13

What is onchocercal dermatitis cause by?

Answer 13

Antigen release from dying microfilaria

Question 14

How do you diagnose Onchocerca cervicalis?

Answer 14

Skin biopsy

Question 15

What is the differential for Onchocerca cervicalis?

Answer 15

Hypersensitivity to biting flies

Question 16

What is the definitive host of Onchocerca lupi?

Answer 16

Dogs and cats

Question 17

What is Onchocerca lupi the causative agent of?

Answer 17

Canine onchocercosis

Acute and chronic ocular disease

Question 18

What causes patent infections with Onchocerca lupi?

Answer 18

Large numbers of microfilaria

Question 19

What are the signs associated with canine onchocercosis?

Answer 19

Conjunctivitis
Discomfort
Periorbital swelling
Exophthalmos
Photophobia
Lacrimation
Dischrage
Periocular tissue
Granulomatous nodules
Cysts

Question 20

What is the definitive host of Acanthocheilonema reconditum?

Answer 20

Dogs

Question 21

What are the intermediate hosts of Acanthocheilonema reconditum?

Answer 21

Fleas (Ctenocephalides felis, C. canis, Pulex iriitans)

Question 22

Where is Acanthocheilonema reconditum microfilaria found?

Answer 22

In blood

Question 23

Is Acanthocheilonema reconditum pathogenic or nonpathogenic?

Answer 23

Nonpathogenic

Question 24

What is Acanthocheilonema reconditum an important differential of?

Answer 24

Dirofilaria immitis, which is pathogenic

Question 25

What is the genus and species of heartworms?

Answer 25

Dirofilaria immitis

Question 26

What is the DH of Dirofilaria immitis?

Answer 26

Domestic dog is the most prevalent Domestive cat Ferrets (rare)

Question 27

What are the dead-end hosts of Dirofilaria immitis?

Answer 27

Bears Raccoons Beavers Humans

Question 28

In humans, what can Dirofilaria immitis be misinterpreted as?

Answer 28

Neoplasia

Question 29

What is the IH of Dirofilaria immitis?

Answer 29

Mosquitoes

Question 30

What are the reservoir hosts of Dirofilaria immitis?

Answer 30

Red wolf Grey fox Red fox Coyote

Question 31

What is the Dirofilaria immitis life cycle in a dog?

Answer 31

Mosquito takes a blood meal (L3 enters skin) L4 migrate toward thorax, circulatory system Adults in pulmonary arteries and right heart Female produces microfilariae Mosquito takes a blood meal L1 L2 L3 migrate to mouth parts

Question 32

What are the required hosts of Dirofilaria immitis?

Answer 32

Definitive host (susceptible population) Intermediate host (susceptible mosquito species) Reservoir hosts Stable mosquito population (Anopheles spp., Aedes spp., Culex spp.)

Question 33

What is the pathology if there is a higher worm burden?

Answer 33

More severe heart/lung disease

Question 34

What are the early pathologic changes with heartworm?

Answer 34

Due to inflammatory processes in/around arteries of lower lungs

Question 35

What are the late pathologic changes with heartworm?

Answer 35

Heart may enlarge and become weakened due to increased workload Congestive heart failure

Question 36

What happens to very active/ working dogs with heartworms?

Answer 36

Severe disease with fewer worms

Question 37

Describe heartworm disease in dogs

Answer 37

Cardiopulmonary Primary due to adults in pulmonary arteries Narrowing/occlusion of pulmonary arteries Disrupts intima Leads to pulmonary hypertension

Question 38

What does pulmonary hypertension cause?

Answer 38

Dilation of right ventricle | Compensatory myocardial hypertrophy

Question 39

What occurs with congestive heart failure?

Answer 39

Ascites Hydrothorax Hydropericardium

Question 40

What can parasites in the heart do?

Answer 40

May trigger mechanical valvular damage/endocarditis

Question 41

What is the progression of clinical signs with heartworms in dogs?

Answer 41

Early: Inapparent Mild: Cough Moderate: Cough, exercise intolerance, abnormal lung sounds Severe: Dyspnea, hepatomegaly, syncope, ascites, abnormal heart sounds, death

Question 42

What is the approved heartworm treatment?

Answer 42

Adulticide therapy

Question 43

What is used in adulticide therapy?

Answer 43

Melarsomine dihydrochloride

Question 44

What is used as a preventive for heartworms?

Answer 44

Macrocylic lactones

Question 45

What is adulticide theapy effective on?

Answer 45

Worms greater than 4 months post-infection

Question 46

What are macrocyclic lactones effective against?

Answer 46

L3 and L4

Question 47

What is caval syndrome?

Answer 47

Acute disease/clinical emergency caused by a large number of worms Increased venous pressure

Question 48

What are the clinical signs of caval syndrome?

Answer 48

``` Acute onset of weakness/anorexia Dyspnea Collapse Pale mucous membranes +/- jaundice Bilirubinemia Bilirubinuria Hemoglobinuria ```

Question 49

What is the PPP of heartworms in cats?

Answer 49

7-8 months

Question 50

What is the lifecycle of heartworms in a cat?

Answer 50

Infected mosquito takes a blood meal L3 to enter skin L3 molt to L4; L4 molt to adult Adults arrive in pulmonary vasculature

Question 51

What are the 2 stages of heartworm disease in cats?

Answer 51

When parasites arrive in pulmonary vasculature | When adult heartworms die

Question 52

What are clinical signs associated with acute phase of heartworm disease in cats?

Answer 52

Subside as worms mature Histopathologic lesions evident when cat clears infection Occlusive medial hypertrophy of small pulmonary arterioles

Question 53

How frequently do cats become microfilaremic?

Answer 53

Rarely

Question 54

What is Wolbachia pipientis?

Answer 54

Intracellular gram-negative bacteria

Question 55

What does Wolbachia pipientis play a role in?

Answer 55

Pathogenesis and host immune response

Question 56

What is Wolbachia pipientis necessary for?

Answer 56

Dirofilaria immitis to reproduce/thrive

Question 57

How do you treat Wolbachia pipientis?

Answer 57

Doxycycline